Our long range goal is to understand how E. chafeensis and other ehrlichial organisms are maintained in nature. As a major objective in pursuit of this goal, this application proposes to develop the domestic goal as a model of E. chafeensis vertebrate infection. The central hypothesis is that domestic goats can serve as a much-needed surrogate to white-tailed deer in laboratory based studies of E. chafeensis reservoir infection dynamics. The rationale behind the proposed research is that goats could provide a superior laboratory model of reservoir host infection to white-tailed deer. Goats have a much more tractable nature than deer and they remain easy to handle throughout their life. This docile nature allows greater latitude in the design of infection studies and reduces the risk of handling-associated injury. In addition, goats are more widely available than deer for research, a higher degree of similarity can be obtained between experimental animals due to controlled inbreeding, they are easily raised in tick-free (and thus Ehrlichia-exposure free) facilities, and a larger variety of laboratory reagents are available for work with goats. In short, a goat model of vertebrate reservoir infection, once developed, would allow design and conduct of experiments not readily possible with deer. To accomplish the objective of this application, we will pursue four specific aims: (1) determine how E. chafeensis infection develops and is maintained in domestic goats, (2) evaluates the persistence of E. chafeensis infection in the absence of re-exposure, domestic goats, (2) evaluate the persistence of E. chafeensis infection in the absence of re-exposure, (3) evaluate the response of goats to multiple re-challenge with a homologous strain of E. chafeensis, and (4) transmit E. chafeensis from infected to naive domestic goats via tick feeding. At the completion of this research we expect to have developed an alternative ruminant model for studying E. chafeensis within the vertebrate reservoir host by characterizing the course of E. chafeensis infection within the domestic goal. Additionally, we will have evaluated both the persistence of infection in goats in the absence of re-exposure and the response of goats to multiple, frequent re-exposure, as well as have developed a natural model of infection in goats via tick feeding. The development of this model and its subsequent application in future experiments will facilitate understanding about the dynamics of E. chafeensis infection in the natural wild reservoir host. New control strategies could result.